Page 725 - Master Catalog 2017, Inch

Technical Information
TopThread
™

American Buttress (7° Pressure Flank Leading) NTB-A Inserts • Push Type

Insert vs. Toolholder Orientation
chuck chuck
counter-clockwise counter-clockwise external internal
rotation rotation
7º
NTB-2RA
feed
NTB-3RA
NTB-4RA
NTB-2LA seating
7° pressure fl ank NTB-3LA surface
of the thread being NTB-4LA seating in bar
the leading fl ank 7º surface
in toolholder
feed insert
insert notch
NTB-2RA 7° pressure fl ank notch
NTB-3RA of the thread being
NTB-4RA the leading fl ank NTB-2LA
NTB-3LA
NTB-4LA
external buttress internal buttress
7° pressure fl ank leading 7° pressure fl ank leading
Reference Dimensions Infeed Angle vs. Chip Load: 7° Pressure Flank Leading
“A” reference
.010" infeed
.010" infeed
nose radius .007" chip load
.0052"
.0039" chip load
chip load .0012"
D maximum chip load
depth with “A”
style insert
15º infeed angle 0º infeed angle
feed direction feed direction
NTB-A insert
insert D “A” ref. nose radius pitch based on
(inch) (inch) (inch) maximum radius
NTB-2A .133 .024 .002–.004 16–20 TPI
NTB-3A .171 .031 .005–.008 8–16 TPI
NTB-4A .218 .049 .008–.012 4–6 TPI
NOTE: For balanced chip load, 15° infeed angle is suggested.
Internal Threading Limitations

internal threading limitations internal threading limitations
NTB-2A Buttress threading inserts NTB-3 and NTB-4A Buttress threading inserts

TPI nominal minimum minor TPI nominal minimum minor
thread size diameter thread size diameter
(inch) (inch)
8 1-3/4 1.600 4* 2-1/2 2.200
5 2-1/4 2.010
10 1-5/8 1.505
6 2 1.800
12 1-1/2 1.400
8 1-3/4 1.600
16 1-1/4 1.175
10 1-5/8 1.505
20 1-1/16 1.002 12** 1-1/2 1.400
*NTB-4A insert only.
**Can cut 16 or 20 threads per inch provided minor diameter is 1.375" or larger.
Threads per Inch vs. Maximum Root Radius Chart (Inch)

TPI 20 16 12 10 8 6 5 4 3 2-1/2 2 1-1/2 1-1/4 1
maximum root radius .0036 .0045 .0059 .0071 .0089 .0119 .0143 .0179 .0238 .0268 .0375 .0476 .0572 .0714
NOTE: Special Buttress forms are available upon request.

widia.com F99

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